Processing device and method of maintaining the device

ABSTRACT

A film processing device using vaporized liquid source capable of confirming the flow control accuracy of flow control equipment such as a mass flow controller ( 15 ) controlling the flow of the liquid source without separating the flow control equipment from piping and disassembling the piping, comprising a bypass passage ( 41 ) for bypassing a part of a washing fluid feed passage ( 32 ) for feeding washing fluid to a liquid source feed passage ( 12 ) and a flowmeter such as an MFM ( 42 ), wherein the washing fluid is allowed to flow to the mass flow controller ( 15 ) through the MFM ( 42 ), and the flow of the washing fluid detected by the MFM ( 42 ) is compared with a target flow set in the mass flow controller ( 15 ) to check whether the mass flow controller ( 15 ) operates normally or not.

FIELD OF THE INVENTION

The present invention relates to a processing device and a method ofmaintaining same for use in a film forming process on a substrate suchas semiconductor wafer, using a liquid source.

BACKGROUND OF THE INVENTION

In a film forming process on a semiconductor wafer (hereinafter refer toas wafer), a liquid source can be used. For example, when forming atantalum oxide film which is used as DRAM's capacitor film, a liquidsource, PET (Tantalum Pentaethoxide: Ta(OC₂H₅)₅) is used. When carryingout the film forming process, PET is transferred from a liquid sourcetank to a vaporizer through a piping, and vaporized therein. The PETflow rate to the vaporizer is controlled by a mass flow controller,which is a liquid flow controller, installed at the piping. In additionto vaporized PET, oxygen gas is supplied into a processing vessel wherea wafer is loaded, to perform a film forming process.

When replacing the liquid source tank or the vaporizer, they areseparated from the piping. Since PET solidifies when it comes in contactwith moistures, the inside of the piping must be thoroughly washed by awashing fluid, such as alcohol to completely remove PET prior toexposing the piping to the atmosphere. Further, after coupling thepiping, air must be completely forced out from the inside of the piping.If cleaning is not performed sufficiently, residual PET inside thepiping reacts with the moistures in the air and solidifies, therebyattaching itself to the inside of the piping. Still further, if thewashing fluid's water content is high, PET reacts with the moistures inthe washing fluid and solidifies similarly. The mass flow controllergauges a fluid flow rate, based on the difference of heat transfers fromthe fluid at an upstream and a downstream point of a flow sensor.Therefore, if solidified PET is attached to the inside of the mass flowcontroller, the heat transfer is altered and reading (sensing) erroroccurs so that the PET flow rate may be several times higher than a rateset to the mass flow controller.

If PET flow rate deviates from a set flow rate, it is possible that thecapacity of a capacitor cannot be obtained as planned. If the flow rateof PET is greater than a set flow rate, the amount of PET consumptionbecomes so high that not only the liquid source tank needs to bereplaced frequently, the cleaning cycle of the processing vessel becomesshort as well. Further, if the reading (sensing) accuracy of the massflow controller declines, the integrating flow rate management bycomputer cannot be properly performed.

In order to prevent such problem, the mass flow controller isperiodically separated from the piping and tested. This test isconducted in the following manner: alcohol is sent into the mass flowcontroller and the alcohol amount is measured by a mess cylinder, andthe reading from the cylinder is compared with the flow rate set to themass flow controller. However, the amount of PET used during filmforming is small and the type of mass flow controller used is also forlow flow rate applications, it is difficult to measure precisely theflow amount by using the mess cylinder.

Before separating the mass flow controller from the piping, the insideof the piping and the mass flow controller are cleaned. However, ifcleaning is not performed sufficiently, residual PET inside the massflow controller reacts with moistures in the air and becomes solidified.Further, if the air that gets into the piping is not completely removedafter the testing is completed and the mass flow controller isreinstalled in the piping, there is a concern for PET solidificationwhen it is sent through the piping. Since such solidified PET becomes,so to speak, similar to ceramic, it is practically impossible to cleanand remove the solidified PET, and the mass flow controller must bereplaced. Namely, there is a concern that malfunctioning of a mass flowcontroller can be attributed to the very process employed to confirm themass flow controller's proper operation.

SUMMARY OF THE INVENTION

The present invention has been made under such a background. It is,therefore, a first object of the present invention to provide atechnology capable of performing accurate testing of flow controlequipment of a liquid source, without a need to separate the equipmentfrom the feed passage of a liquid source or to disassemble the passage.

A second object of the present invention is to achieve theaforementioned first object without lowering the efficiency of cleaningthe feed passage of the liquid source.

In accordance with one aspect of the present invention for achieving theobjects, there is provided a processing device, including: a processingvessel in which a process is performed on an object to be processed byusing a liquid source; a liquid source feed passage installed so as tosupply the liquid source into the processing vessel from a liquid sourcefeed source; a flow controller, installed at the liquid source feedpassage, for controlling a flow rate of the liquid source flowingthrough the liquid source feed passage at a target flow rate; a washingfluid feed passage installed so as to supply a washing fluid from awashing fluid feed source to an upstream side of the flow controller inthe liquid source feed passage; and a testing unit, installed at thewashing fluid feed passage, having at least one of a function formeasuring a flow rate of the washing fluid flowing through the washingfluid feed passage and that for controlling the flow rate of the washingfluid flowing through the washing fluid feed passage at a target flowrate, wherein the processing device is configured to enable the washingfluid to flow to the flow controller through the testing unit.

Further, the processing device of the present invention may include adetermination unit for determining whether the flow controller properlyoperates or not on the basis of a comparison of a target flow rate ofthe washing fluid set in the flow controller with an actual flow rate ofthe washing fluid measured by the testing unit in case of flowing thewashing fluid to the flow controller through the testing unit, or acomparison of an actual flow rate of the washing fluid measured by aflow sensor prepared in the flow controller with a target flow rate setin the testing unit in case of flowing the washing fluid to the flowcontroller through the testing unit.

In accordance with another aspect of the present invention, there isprovided a processing device, including: a processing vessel in which aprocess is performed on an object to be processed by using a liquidsource; a liquid source feed passage installed so as to supply theliquid source into the processing vessel from a liquid source feedsource; a flow controller, installed at the liquid source feed passage,for controlling a flow rate of the liquid source flowing through theliquid source feed passage at a target flow rate; a washing fluid feedpassage installed so as to supply a washing fluid from a washing fluidfeed source to an upstream side of the flow controller in the liquidsource feed passage; a bypass passage whose one end is connected to thewashing fluid feed passage, and, at the same time, the other end isconnected to the washing fluid feed passage or the liquid source feedpassage, and which bypasses a part of the washing fluid feed passage; atesting unit, installed at the bypass passage, having at least one of afunction for measuring a flow rate of the washing fluid flowing throughthe bypass passage and that for controlling the flow rate of the washingfluid flowing through the bypass passage at a target flow rate; and avalve for switching between a first state, in which the washing fluid issupplied into the liquid source feed passage through the bypass passage,and a second state, in which the washing fluid is supplied into theliquid source feed passage without passing through the bypass passage,wherein the processing device is configured to enable the washing fluidto flow to the flow controller through the testing unit installed at thebypass passage.

Further, the processing device of the present invention may include aflow adjuster, which is installed at the part of the washing fluid feedpassage and controls a flow rate of the washing fluid supplied into theliquid source feed passage through the part of the washing fluid feedpassage.

Still further, the processing device of the present invention mayinclude a flow adjuster, which is installed at an upstream side of thepart of the washing fluid feed passage and at least controls a flow rateof the washing fluid supplied into the liquid source feed passagethrough the part of the washing fluid feed passage.

In accordance with still another aspect of the present invention, thereis provided a processing device, including: a processing vessel in whicha process is performed on an object to be processed by using a liquidsource; a liquid source feed passage installed so as to supply theliquid source into the processing vessel from a liquid source feedsource; a flow controller, installed at the liquid source feed passage,for controlling a flow rate of the liquid source flowing through theliquid source feed passage at a target flow rate; a testing unit forhaving at least one of a function for measuring a flow rate of a washingfluid flowing through the testing unit and that for controlling the flowrate of the washing fluid flowing through the testing unit at a targetflow rate; a first washing fluid feed passage connected to the liquidsource feed passage, and installed such that the washing fluid issupplied to an upstream side of the flow controller in the liquid sourcefeed passage without passing through the testing unit; and a secondwashing fluid feed passage connected to the liquid source feed passageand, at the same time, having a part where the testing unit is placed,the second washing fluid feed passage being installed such that thewashing fluid is supplied to an upstream side of the flow controller inthe liquid source feed passage through the testing unit.

Further, in the processing device of the present invention, at least aportion of the first washing fluid feed passage may be shared with atleast a portion of the second washing fluid feed passage. Further, theprocessing device of the present invention may include a flow adjusterinstalled at a part of the first washing fluid feed passage not sharedwith the second washing fluid feed passage. Still further, theprocessing device of the present invention may include a flow adjusterinstalled at an upstream side of the testing unit in said at least theportion of the first washing fluid feed passage shared with the secondwashing fluid feed passage.

Meanwhile, in case where at least a portion of the first washing fluidfeed passage is shared with at least a portion of the second washingfluid feed passage, it is preferable that the processing device includesa common washing fluid feed source for feeding the washing fluid to thefirst and the second washing fluid feed passage.

Further, there may be no shared part in the first and the second washingfluid feed passage. In this case, two washing fluid feed sources may beinstalled.

In accordance with still another aspect of the present invention, thereis provided a processing device, including: a processing vessel in whicha process is performed on an object to be processed by using a liquidsource; a liquid source feed passage installed so as to supply theliquid source into the processing vessel from a liquid source feedsource; a flow controller for controlling a flow rate of the liquidsource flowing through the liquid source feed passage, wherein the flowcontroller includes a flow detection unit, a flow control valve, and acontroller for adjusting opening ratio of the flow control valve suchthat a flow rate of a fluid detected by the flow detection unit becomesa target flow rate; a memory unit for storing a relationship between thedata related to the target flow rate and that related to the openingratio of the flow control valve for a case where the flow controllerproperly operates; and a determination unit for determining whether theflow controller properly operates or not on the basis of a comparisonresult of the relationship stored in the memory unit with a relationshipbetween the data related to the target flow rate and that related to theopening ratio of the flow control valve in case where the flowcontroller is actually operated.

In accordance with still another aspect of the present invention, thereis provided a method of maintaining a processing device in which aliquid source is supplied into a processing vessel through a flowcontroller installed at a liquid source feed passage, the methodincluding the steps of: flowing a washing fluid to the flow controllerthrough a testing unit having at least one of a function for measuring aflow rate of the washing fluid and that for controlling the flow rate ofthe washing fluid at a target flow rate; comparing a target flow rate ofthe washing fluid set in the flow controller with an actual flow rate ofthe washing fluid measured by the testing unit in case of flowing thewashing fluid to the flow controller through the testing unit, orcomparing an actual flow rate of the washing fluid measured by a flowsensor prepared in the flow controller with a target flow rate set inthe testing unit in case of flowing the washing fluid to the flowcontroller through the testing unit; and determining whether the flowcontroller properly operates or not on the basis of the comparison.

In accordance with still another aspect of the present invention, thereis provided a method of maintaining a processing device in which aliquid source is supplied into a processing vessel through a flowcontroller installed at a liquid source feed passage, the methodincluding: cleaning process for cleaning the liquid source feed passageby flowing a washing fluid to the liquid source feed passage at a firstflow rate; and testing process for testing the flow controller byflowing the washing fluid to the flow controller at a second flow rate,wherein the testing process includes the steps of, flowing the washingfluid to the flow controller through a testing unit having at least oneof a function for measuring a flow rate of the washing fluid and thatfor controlling a flow rate of the washing fluid at a target flow rate,comparing a target flow rate of the washing fluid set in the flowcontroller with an actual flow rate of the washing fluid measured by thetesting unit in case of flowing the washing fluid to the flow controllerthrough the testing unit, or comparing an actual flow rate of thewashing fluid measured by a flow sensor prepared in the flow controllerwith a target flow rate of the washing fluid set in the testing unit incase of flowing the washing fluid to the flow controller through thetesting unit, and determining whether the flow controller properlyoperates or not on the basis of the comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing of the total configuration of a processing device inaccordance with a preferred embodiment of the present invention.

FIG. 2 shows a flowchart that describes the correction sequence of amass flow controller in the processing device of FIG. 1, in accordancewith a method of the present invention.

FIG. 3 is a drawing of the total configuration of a processing device inaccordance with another preferred embodiment of the present invention.

FIG. 4 shows a view of the total configuration of a processing device inaccordance with still another preferred embodiment of the presentinvention.

FIG. 5 shows a view of the total configuration of a processing device inaccordance with still another preferred embodiment of the presentinvention.

FIG. 6 shows a view of a configuration of the main part a processingdevice in accordance with still another preferred embodiment of thepresent invention.

FIG. 7 shows a view of a configuration of the main part a processingdevice in accordance with still another preferred embodiment of thepresent invention.

FIG. 8 is a graph that schematically shows a relationship between a setflow rate of a mass flow controller and a control voltage for the valveopening ratio.

FIG. 9 shows a view of the total configuration of a processing device inaccordance with still another preferred embodiment of the presentinvention.

FIG. 10 shows a flowchart that illustrates the cleaning process of thefeed passage of a liquid source in the processing device of FIG. 9.

FIG. 11 shows a view of the total configuration of a processing devicein accordance with still another preferred embodiment of the presentinvention.

FIG. 12 shows a view of the total configuration of a processing devicein accordance with still another preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a preferred embodiment of a processing device in accordancewith the present invention, and is a view of a substrate processingdevice for forming a tantalum oxide film (Ta₂O₅) on a surface of asemiconductor wafer (hereinafter refer to as wafer) W. In FIG. 1,reference numeral 11 indicates a liquid source tank (liquid source feedsource) where tantalum pentaethoxide [Ta(OC₂H₅)₅: hereinafterabbreviated as “PET”] of a liquid source, which is used as a rawmaterial for film forming gas, is stored. The liquid source tank 11 isconnected to a processing vessel 2, in which a film forming process (gasprocess) is carried out on the wafer W, through a liquid source feedpassage 12 made of a piping.

The liquid source tank 11 is connected to a He gas supply unit 14through a gas line 13 and a valve V0, and the He gas sent into theliquid source tank 11 from the He gas supply unit 14 drives PET in theliquid source tank 11 to the liquid source feed passage 12. He gas has alow solubility in PET. As a result, when PET is vaporized in a vaporizer16, it does not occur that dissolved He gas in PET would vaporize andsuddenly expand by the heat from a heater to disturb the control of PETflow rate. Based on this advantage, He gas is used preferably butanother gas species can be used instead.

Along the liquid source feed passage 12, the equipment are installed inthe following order from the upstream: valves V10, V9, and V1, a massflow controller (hereinafter refer to as “MFC”) 15, which is a liquidflow controller, a vaporizer 16, and a valve V2.

While the MFC 15 is an integrated unit, which includes a flow controlvalve, a flow sensor (flowmeter), and a controller (all of which are notshown in FIG. 1), the controller regulates the opening ratio of the flowcontrol valve on the basis of a set flow rate (i.e., a target flow rateset in the MFC 15) and a reading from the flow sensor. Since the PETflow rate when forming a tantalum oxide film is a very small amount suchas about 0.2 cc/minute, the MFC 15 employed is capable of controllingthe flow rate in the range of 0.10 cc/minute to 0.50 cc/minute.

Instead of installing the MFC 15 as an integrated unit, the mass flowcontroller can be composed so that the flow control valve, the flowsensor, and the controller, are individually provided. For example, itis possible to install a mass flow meter already including a controllerinstead of the MFC 15 and to install inside the vaporizer 16 a flowcontrol valve whose opening ratio is controlled by the correspondingcontroller.

A carrier gas supply source 17 for supplying a carrier gas such as Hegas is connected to the vaporizer 16. In the vaporizer 16, the carriergas is heated to about 160° C. by a built-in heater which is not shown.PET is sent into an actuator (not shown) inside the vaporizer 16 withheated carrier gas, is vaporized therein, and is sent to the processingvessel 2 as a film forming gas.

In the processing vessel 2, a mounting table 21 for mounting the wafer Wis disposed. In the mounting table 21, a heater (not shown) for heatingthe wafer W from the rear side during the film forming process isinstalled. On a ceiling of the processing vessel 2, a shower head 22having multiple holes (not shown) in its lower part is disposed. Theshower head 22 supplies both a film forming gas, which is sent throughthe aforementioned liquid source feed passage 12, and an oxygen (O₂) gassupplied from an oxygen gas supply unit 23, towards the wafer W mountedon the mounting table 21.

An exhaust port 24 is disposed in a bottom portion of the processingvessel 2, and the portion is connected to an exhaust line 25 made of apiping. The other end of the exhaust line 25 is connected to a vacuumpump (exhaust means) 26. A valve V3 is installed in the exhaust line 25,and a bypass passage 18, which is branched from a junction node P1between the vaporizer 16 and the valve V2, is connected between thevalve V3 of the exhaust line 25 and the vacuum pump 26. The bypasspassage 18 is utilized when cleaning the liquid source feed passage 12.

A valve V4 is installed in the bypass passage 18, and a flowing path ofa fluid can be changed in the downstream of the junction node P1, byworking with and switching valves V2 and V4.

Subsequently, the part that is operated for cleaning the liquid sourcefeed passage 12 and the MFC 15 test is explained.

In FIG. 1, reference numeral 31 is a washing fluid tank (washing fluidfeed source), in which a washing fluid such as ethanol (C₂H₅OH) forwashing down PET inside the liquid source feed passage 12 is stored.Since ethanol is hydrophilic, by passing it through a new piping systemor a reconnected piping system after maintenance and repair, it ispossible to remove moistures remaining on an inner wall of the piping.Although ethanol tends to contain moisture, it is preferable that thewater content of ethanol is maintained 1000 ppm or less. The washingfluid is not limited to ethanol so that an organic solvent such asanother alcohol species, acetone, or the like may be used. The washingfluid is not necessarily limited to hydrophilic substances and it may bea hydrophobic liquid chemical, for example, hexane or octane.

A washing fluid feed passage 32 is extended from a washing fluid tank31, and is connected to the liquid source feed passage 12 at a point(junction node P2) between the valves V1 and V9. The washing fluid tank31 is connected to a nitrogen (N₂) gas supply source 34 through a gassupply line 33. By opening a valve V5 installed in the gas supply line33, the washing fluid in the washing fluid tank 31 is pushed to thewashing fluid feed passage 32 by a pressure of nitrogen gas, therebymoving towards the liquid source feed passage 12.

Along the washing fluid feed passage 32, beginning from the washingfluid tank 31 side, a needle valve 35, which is a flow controller of thewashing fluid, and valves V6 and V7 are installed in that order.Further, a discharge line 30 branches out between the valves V9 and V10of the liquid source feed passage 12. The discharge line 30 is connectedto a drain tank (not shown) through a valve V11. The discharge line 30is used when cleaning the liquid source feed passage 12.

To the washing fluid feed passage 32, a bypass passage 41 that bypassesthe section where the needle valve 35 and the valve V6 are installed inthe washing fluid feed passage 32, is connected. In the bypass passage41, from the upstream, a mass flow meter (hereinafter refer to as “MFM”)42 used as a testing unit and a valve V8, are installed in that order.By interchanging the valves V6 and V8, it is possible to selectivelysend the washing fluid to either the section where the needle valve 35of the washing fluid feed passage 32 is installed or the bypass passage41 in which the MFM is installed. Namely, in the processing device, afirst washing fluid feed passage, which starts from the washing fluidtank 31 and connects to the liquid source feed passage 12 through theneedle valve 35, and a second washing fluid feed passage, which shares apart of the first washing fluid feed passage, and starts from thewashing fluid tank 31 and connects to the liquid source feed passage 12through the MFM 42, are installed.

The needle valve 35 is used for adjusting the flow rate of the washingfluid when cleaning the liquid source feed passage 12 and/or theequipment such as MFC 15 installed in the liquid source feed passage 12.The needle valve 35 is adjusted to allow the washing fluid at a rate ofabout 5 cc/minute. Since it is not necessary to precisely regulate theflow rate of the washing fluid during cleaning, the flow controller ofthe washing fluid need not have the capability to monitor and toautomatically control the fluid flow rate through the controller so thatit is sufficient as long as the flow controller is capable of manuallyadjusting the flow rate roughly. In the present embodiment, while theneedle valve 35 is used as an inexpensive flow controller satisfyingsuch demand, another type of flow controller may be used.

Since the MFM 42 is installed for testing the MFC 15, it has ameasurement range corresponding to the aforementioned flow control rangeof the MFC 15, for example, from 0.10 cc/minute to 0.50 cc/minute. It ispreferable that the reading (sensing) accuracy of the MFM 42 issubstantially equal to or greater than that of the MFC 15. Further,another type of flowmeter may be used provided that its flow ratereading accuracy is just as good.

The maximum flow rate of the washing fluid through the MFM 42, which hasa reading range of 0.10 cc/minute to 0.50 cc/minute described above, issmaller than a desirable flow rate of the washing fluid for cleaning (inthe present embodiment, about 5 cc/minute). Therefore, the bypasspassage 41 bypassing the MFM 42 is installed so that a large amount ofthe washing fluid desired for cleaning can run through.

The MFC 15 and the flowmeter 42 are connected to a computer 5. Thecomputer 5 is preferably set up as a part of a system controller (notshown), which controls the overall operation of the processing device.The computer 5 monitors the proper operation of MFC 15, on the basis ofa set flow rate of the MFC 15 or a flow rate detected by a built-in flowsensor of the MFC 15, and a flow rate measured by the MFM 42, whenrunning the washing fluid to the MFC 15 through the bypass passage 41.Further, the computer 5 has a display function to indicate in a displayunit (not shown) that the MFC 15 is proper when it determines that theMFC 15 is properly operating. On the other hand, the computer 5 displaysin the display unit (not shown) that the MFC 15 is improper when theoperation of the MFC 15 is determined to be improper. Still further, thecomputer 5 may have a function to signal an alarm when the MFC 15 isdetermined to be improper and a function to transmit a signal forpreventing starting of a film forming process.

Next, the operation is discussed. First, the film forming process isdiscussed briefly. The wafer W is loaded onto the mounting table 21through a gate valve (not shown), which is installed at the side portionof the processing vessel 2. The vacuum pump 26 operates and the insideof the processing vessel 2 is maintained at a predetermined vacuum levelby adjusting the opening ratio of the valve V3. The wafer W is heated bya heater (not shown), which is installed in the mounting table 21,whereby the wafer W's surface temperature reaches a predeterminedprocessing temperature. Under this condition, when PET vapor and oxygengas are delivered onto the wafer W through the shower head 22, atantalum oxide (Ta₂O₅) film is formed over the entire surface of thewafer W by a chemical vapor deposition mechanism. At this time, theaforementioned system controller (not shown) adjusts the flow rate ofPET running through the inside of the liquid source feed passage 12 to apredetermined flow, e.g., 0.12 cc/minute, by the MFC 15, and adjusts theflow rate of the oxygen gas to a predetermined flow rate by a gas flowcontroller (not shown).

As a result of repeatedly performing the film forming process to consumePET, if the tank 11 becomes empty, it is replaced. The replacementprocedure is carried out in the following manner: the upstream pipingfrom the valve V10 of the liquid source feed passage 12 is disconnected,and a piping equipped with a new tank 11 is connected to the valve V10.Prior to this replacement procedure, the inside of the piping locateddownstream of the valve V10 is cleaned to remove PET.

When performing the cleaning, the valve V8 is closed, the valve V6 isopened, and the needle valve 35 is adjusted to supply the washing fluidat a flow rate of about 5 cc/minute. At this time, by closing the valvesV1 and V10, and opening the valves V7, V9, and V11, the washing fluidwould clean the area between the valve V1 of the liquid source feedpassage 12 and the valve V10 to remove PET therein, and thereafter, thewashing fluid with PET is discharged to a drain tank (not shown) througha discharge line 30. Further, since it is not necessary to exactlycontrol the flow rate of the washing fluid during cleaning as describedabove, the flow rate control of the washing fluid is conducted bymanually adjusting the opening ratio of the needle valve 35, based onexperiences.

Subsequently, the MFC 15 testing is performed as follows. First, thevalves V6, V9, and V2 are closed, and the valves V8, V7, V1, and V4 areopened (step S1 of FIG. 2). Thereafter, the valve V5 is opened to supplythe washing fluid into the washing fluid feed passage 32. Thecorresponding washing fluid runs through the MFC 15 via the MFM 42,vaporizes in the vaporizer 16, and is exhausted through the bypasspassage 18 (step S2). At this time, the flow rate of the washing fluidis set to a flow rate within a range controllable by the MFC 15, e.g., aflow rate (0.12 cc/minute) corresponding to that of PET in film forming.The computer 5, by comparing the set flow rate of the MFC 15 (targetflow rate preset in the MFC 15) with a flow rate measured by the MFM 42,determines whether both flow rates match, for example determines whetherthe difference of the flow rates is within a permissible range (forexample, within the permissible range of measurement error in thedevice) or not (step S3). If the result is within the permissible range,the washing fluid is running at a set flow rate in the MFC 15, so thatthe MFC 15 operates properly, in this case, a message is displayed asproper in a display unit such as a monitor (not shown) (step S4).However, if the result is outside the permissible range, the washingfluid is not running at a set flow rate in the MFC 15, so that thecomputer 5 displays an improper operation message (step S5), and forexample, an alarm is activated.

In case the message indicates an improper operation, it is highly likelythat solidified PET is attached inside the MFC 15 so that the MFC 15 isreplaced with a new one.

When replacing the MFC 15, the liquid source feed passage 12 isdisassembled, and each part thereof contacts with the air. As a result,there is a concern that PET on the parts would react with moisture inthe air as described above, and solidify. Therefore, before and afterthe disassembling procedure, cleaning of the liquid source feed passage12 is performed. In the procedure, the valves V6 and V8 areinterchanged, and the washing fluid is supplied to the liquid sourcefeed passage 12 through the needle valve 35. Further, at this time, asignal is given for the MFC 15 that the opening ratio of the built-inflow control valve of the MFC 15 is fully open. Accordingly, it ispossible to run the washing fluid into the MFC 15 with a flow rategreater than the flow control range when the MFC 15 is properlyoperating.

In the aforementioned embodiment, the MFM 42 is installed in the washingfluid feed passage 32, the washing fluid flows into the MFC 15, whichcontrols the flow rate of the liquid source, and the MFC 15 testing isperformed by comparing the set flow rate of the MFC 15 with the measuredflow rate of the MFM 42. Therefore, the MFC 15 testing can be performedwithout separating it. As a result, it is possible to avoid such a riskthat moisture in the air and PET would react when detaching andattaching the MFC 15.

Further, in the aforementioned embodiment, a bypass passage 41 isconnected to the washing fluid feed passage 32, in which the MFM 42 usedin the MFC testing 15 is installed. Thus, fast cleaning can be performedby sending a large amount of washing fluid when cleaning, whereas whenconducting the MFC 15 testing, a small amount of the washing fluid,corresponding to that of the liquid source when film forming, is sent.

Still further, the arrangement of the bypass passage is not limited tothe configuration of FIG. 1, but the bypass passage can be arranged asillustrated in FIG. 3. In a preferred embodiment shown in FIG. 3, oneend of a bypass passage 41′ is connected to the upstream of the valve V7in the washing fluid feed passage 32, and the other end is connected tothe junction node P3 between the valve V1 of the liquid source feedpassage 12 and the MFC 15. In this case, in the processing device, thereare installed a first and a second washing fluid feed passage, whereinthe first washing fluid feed passage is connected to the junction nodeP2 of the liquid source feed passage 12 through the needle valve 35 fromthe washing fluid tank 31, and wherein the second washing fluid feedpassage shares a part with the first washing fluid feed passage, and atthe same time, is connected to the junction node P3 of the liquid sourcefeed passage 12 through the needle valve 35 and the MFM 42 from thewashing fluid tank 31. In this case, the washing fluid can be suppliedby any one of the first and the second washing fluid feed passage, byproperly interchanging the valves V7, V8, and V1.

Still further, the bypass passage can be arranged, as illustrated inFIG. 4. In a preferred embodiment shown in FIG. 4, one end of a bypasspassage 41″ is connected between the valve V6 of the washing fluid feedpassage 32 and the needle valve 35, and the other end is connected tothe junction node P3 between the valve V1 of the liquid source feedpassage 12 and the MFC 15. In this case, in the processing device, thereare installed a first and a second washing fluid feed passage, whereinthe first washing fluid feed passage is connected to the junction nodeP2 of the liquid source feed passage 12 through the needle valve 35 fromthe washing fluid tank 31, and wherein the second washing fluid feedpassage shares a part with the first washing fluid feed passage, and, atthe same time, is connected to the junction node P3 of the liquid sourcefeed passage 12 through the needle valve 35 and the MFM 42 from thewashing fluid tank 31. In this case, the washing fluid can be suppliedselectively by the first or the second washing fluid feed passage, byproperly interchanging the valves V6, V7, V8, and V1.

Still further, as described in FIG. 11, two washing fluid tanks 31 and31′ may be installed. In this case, in the processing device, there areinstalled a first and a second washing fluid feed passage, wherein thefirst washing fluid feed passage 32 is connected to the junction node P2of the liquid source feed passage 12 through the needle valve 35 fromthe washing fluid tank 31, and wherein the second washing fluid feedpassage 32′ is connected to a junction node P4 of the liquid source feedpassage 12 through the MFM 42 from the washing fluid tank 31′ at thesame time while the second passage does not share any part with thefirst washing fluid feed passage.

Still further, as illustrated in FIG. 12, two washing fluid tanks 31 and31′ can be installed. In this case, in the processing device, there areinstalled a first and a second washing fluid feed passage, wherein thefirst washing fluid feed passage is connected to the junction node P2 ofthe liquid source feed passage 12 through the needle valve 35 from thewashing fluid tank 31, and wherein the second washing fluid feed passageshares a part with the first washing fluid feed passage, and at the sametime, is connected to the junction node P2 of the liquid source feedpassage 12 through the MFM 42 from the washing fluid tank 31′.

The aforementioned configuration can be applied to such a processingdevice that the common liquid source tank 11 and the washing fluid tank31 are installed for a plurality of processing vessels as illustrated inFIG. 5. A preferred embodiment shown in FIG. 5 is based on that of FIG.1, and corresponds to such a configuration that the liquid source feedpassage 12 is split into three branches in the upstream of the valve V9,and, at the same time, the washing fluid feed passage 32 is split intothree branches in the upstream of the valve V7. In the preferredembodiment shown in FIG. 5, by opening the valve V7 corresponding to theMFC 15, which is the object to be calibrated, the MFC 15 can becalibrated as desired by using the MFM 42 that is a common testing unit.Further, for simplification of the drawing in FIG. 5, some units (bypasspassage 18, discharge line 25, valve V3, and vacuum pump 26) disposed inthe lower side of the valve V1 have been omitted, but they are set up inpractice for each processing vessel, as described in FIG. 1.

As for the testing unit, a flow controller may be used instead of theMFM 42 (flowmeter equipment) used in the aforementioned embodiment. Inthis case, a flow controller of which flow control range overlaps withthat of the MFC 15 for liquid source can be used, for example the sametype as MFC 15. The MFC 15 test may be performed by determining whethera detection value of the built-in flow sensor of the MFC 15 matches witha set flow rate of the testing MFC, or reversely, by determining whethera detection value of the built-in flow sensor of the testing MFC matcheswith a set flow rate of the MFC 15.

In this case, a testing MFC 61 may be installed in the upstream of theneedle valve 35 in the washing fluid feed passage 32, as described inFIG. 6, without installing the bypass passages 41, 41′, and 41″. Fromthe consideration of enhancing the cleaning efficiency, it is preferablethat the MFC 61 can permit a flow rate of the washing fluid with anamount greater than a controllable range when properly operating, byfully opening its built-in flow control valve. In case an MFC thatcannot permit a flow rate of the washing fluid more than itscontrollable range when properly operating is used, cleaning isperformed with a flow rate within its corresponding controllable range.In case of the arrangement illustrated in FIG. 6, the flowmeterequipment such as a mass flow meter may be used instead of the MFC 61,but the flow rate of the washing fluid becomes limited by the maximumflow rate permissible by the corresponding flowmeter equipment.

Further, the needle valve 35 may be omitted from the configuration shownin FIG. 6. In this case, the MFC 61 can be used both as a flowcontrolling unit for the washing fluid during cleaning and as a testingunit.

Next, still another preferred embodiment of the present invention isdiscussed with reference to FIGS. 7 and 8. As described in FIG. 7, theMFC 15 includes a flow detection unit (flow sensor) 71, a controller 72for comparing a flow rate detected in the flow detection unit 71 with aset flow rate and outputting an operation signal based on thediscrepancy thereof, and a flow control valve 74 of which opening ratiois adjusted by an actuator 73 based on the operation signal. Referencenumeral 8 indicates a computer, and it has a memory unit 81 and adetermination means 82. In the memory unit 81, the following two typesof data are stored: the data corresponding to a set flow rate of the MFC15 when the washing fluid is sent to the MFC 15 operating properly (forexample, a data representing a set flow rate of the MFC 15, or a datacorresponding to a control signal for setting a set flow rate of the MFC15 sent from the aforementioned system controller to the MFC 15) and thedata corresponding to an opening ratio, which corresponds to the setflow rate (for example, a data corresponding to a signal representing ashift of the actuator 73, or a data representing a control voltage ofthe actuator 73). In a preferred embodiment shown in FIG. 7, the entireconfiguration of the processing device may be the same as that of FIG.1, except that the bypass passage 41, MFM 42, and valve V8 are notinstalled.

In case of testing the MFC 15, a set flow rate of the MFC 15 is adjustedto the same value as that of the memory unit 81 as a flow rate of thewashing fluid of the MFC 15. The computer 8 collects the datacorresponding to the actual opening ratio of the valve at that time(here, a signal representing a shift of the actuator 73), compares inthe determination means 82 whether the data corresponding to the openingratio of the valve stored in the memory unit 81 matches with thecollected data, and determines whether the MFC 15 is properly operatingor not on the basis of the comparison.

FIG. 8 is a graph for illustrating a relationship between set flow ratesof the MFC 15 and valve control voltages corresponding to valve openingratios, wherein a solid line (a) indicates a case where the MFC 15 isproperly operating. If PET attaches to a part involved with flowdetection of the MFC 15, the flow detection sensitivity becomesimprecise. In case where the washing fluid is running at 0.2 cc but onlya detection value of 0.1 cc can be obtained, the opening ratio becomeslarge, so that even with the same set flow rate, the slope becomessteeper, as shown by the solid line (b). Therefore, it is possible todetermine whether the MFC 15 is properly operate or not, by comparing anactual opening ratio value with a stored value of the opening ratio. Incarrying out such a method, a function (for example, the solid line (a)shown in FIG. 8) for showing a relationship between a predetermined setflow and a signal for the opening ratio of the valve is obtained inadvance, and it may be determined whether the set flow during testingand the actual opening ratio of the valve are consistent with thefunction or not.

In accordance with the preferred embodiment shown in FIG. 7, it ispossible to calibrate the MFC 15 without separating it, even when thetesting unit is not installed in the washing fluid feed passage 32.

Next, still another embodiment of the present invention will beexplained with reference to FIG. 9. A processing device shown in FIG. 9is different from that of FIG. 1, as follows.

(1) A branch line 33′ is connected to the gas supply line 33 which isfor supplying a nitrogen gas into the washing fluid tank 31 to therebypush the washing fluid while the branch line 33′ is connected to at adownstream point of the valve V6 in the washing fluid feed passage 32,and, at the same time, a valve V12 is installed in the branch line 33′.

(2) A valve V13 is installed at a downstream point lower than a positionto which the branch line 33′ of the gas supply line 33 is connected,and, by interchanging the valves V12 and V13, the following modes areavailable to be selected: the mode wherein the washing fluid is sent tothe washing fluid feed passage 32 by supplying the nitrogen gas into thewashing fluid tank 31 side; and the mode wherein the nitrogen gas isdirectly sent to the washing fluid feed passage 32 by bypassing thewashing fluid tank 31.

(3) A pressure controller 36 is installed between the nitrogen gassupply source 34 and the valve V5.

(4) The discharge line 30 branched between the valves V9 and V10 of theliquid source feed passage 12 is extended through the drain tank 9, tobe connected to the exhaust line 25 for exhausting the processing vessel2. The drain tank 9 is made of an airtight container, and, to a topsurface thereof, the tank is connected the discharge line 30(30 a) fromthe liquid source feed passage 12 side and the discharge line 30(30 b)from the vacuum pump 26 side, through valves V14 and V15, respectively.

Next, in the processing device shown in FIG. 9, a method for cleaningthe liquid source feed passage 12 is discussed with reference to FIGS. 9and 10. The following explanation assumes a case wherein the liquidsource feed passage 12 is cleaned before it is opened to the air, whenperforming maintenance and repair during equipment replacement such asthe piping, the MFC 15, or the like, or the liquid source tank 11.First, the valves V2 and V10 of the liquid source feed passage 12 areclosed. Then, the valves V9 and V1 between the valves V2 and V10 and thevalve V4 of the bypass passage 18 are opened; the valves V13, V6, and V8are closed; and the valves V5, V12, and V7, and the valves V11, V14, andV15 of the discharge line 30 are opened.

Accordingly, the following two paths are formed: a path for sequentiallyrunning the liquid source feed passage 12 and the bypass passage 18 fromthe nitrogen gas supply source 34 to reach the vacuum pump 26; and apath for sequentially passing the liquid source feed passage 12 and thedischarge line 30 from the nitrogen gas supply source 34 to reach thevacuum pump 26. Therefore, the nitrogen from the nitrogen gas supplysource 34 flows into the liquid source feed passage 12 through thewashing fluid feed passage 32. As a result, PET is sent to the vacuumpump 26 side, and the gas inside the piping is substituted by thenitrogen gas (step S1). In this case, PET remaining in the downstream ofthe junction node P2 is vaporized in the vaporizer 16 and exhaustedthrough the bypass passage 18. In addition, PET present between thejunction P2 and the valve V10 is collected in the drain tank 9 throughthe exhaust line 30(30 a) first, and the nitrogen gas is exhaustedthrough the exhaust line 30(30 b).

In case of not installing the drain tank 9, since PET vaporizes in amoment when flow into the exhaust line 25 from the exhaust line 30, theload of the vacuum pump 26 becomes large. However, by installing thedrain tank 9, like the preferred embodiment of FIG. 9, a buffer forcollecting PET becomes available. Therefore, there is an advantage ofmaking the loading of the vacuum pump 26 small.

Subsequently, the valve V5 of the gas supply line 33 is closed to stopsupplying the nitrogen gas, and the pipings in the downstream of thevalve V5, i.e., the insides of the washing fluid feed passage 32, theliquid source feed passage 12, and the discharge line 30, are exhaustedby the vacuum pump 26 (step S2). Thereafter, the valve V12 in the branchline 33′, V11 in the discharge line 30, and V4 of in the bypass passage18 are closed, and the valves V13 and V6 are opened. Accordingly, thenitrogen gas is supplied into the washing fluid tank 31, whereby thewashing fluid is pushed out from here. At this time, since the washingfluid feed passage 32 and the liquid source feed passage 12 are in adepressurized atmosphere, the washing fluid is sent and filled therein(step S3). After 5 seconds to 30 minutes, the same valve operation asthat of step S1 is performed, so that there are formed a first and asecond fluid path, wherein the first fluid path sequentially runsthrough the liquid source feed passage 12 and the bypass passage 18 fromthe nitrogen gas supply source 34 to reach the vacuum pump 26, andwherein the second fluid path sequentially passes the liquid source feedpassage 12 and the discharge line 30 from the nitrogen gas supply source34 to reach the vacuum pump 26. Then, the washing fluid inside thewashing fluid feed passage 32 and the liquid source feed passage 12 aresent and discharged by the nitrogen gas (step S4). Thereafter, bycontinuously flowing the nitrogen gas, the gas inside the piping issubstituted by the nitrogen gas (step S5).

Then, the valve V5 of the nitrogen gas supply source 34 side is closedto stop supplying the nitrogen gas, in the same manner as step S2, andthe insides of the washing fluid feed passage 32, the liquid source feedpassage 12, and the discharge line 30 are exhausted by the vacuum pump26 (step S6). Continuously, the valve V5 is opened, and, at the sametime, the pressure of the nitrogen gas is adjusted by the pressurecontroller 36, whereby the inside of the piping is filled with thenitrogen gas at the atmospheric pressure (step S7). Then, the valve V5is closed. After cleaning of the piping is finished as described above,the liquid source feed passage 12 is disassembled and opened to the air,and maintenance and repair operations such as equipment exchange e.g.,the piping or the MFC 15, or exchange of the liquid source tank 11 arecarried out.

Further, after completing the maintenance and repair operations andconnecting the liquid source feed passage 12, steps S2 to S6 shown inFIG. 10 are performed. Namely, the inside of the piping is vacuumexhausted and filled with the washing fluid, and then, the nitrogen gasis supplied to discharge the washing fluid. After that, the inside ofthe piping is vacuum exhausted again. As for the washing fluid, ethanolmay be used as mentioned above. Even in a case where a very small amountof moisture is present in the piping when vacuum exhausting ethanol, orpresent in ethanol itself, a mixture of ethanol and water evaporatesfirst (azeotropy) since a boiling point of the mixture is lower thanthat of ethanol. Therefore, practically no residual moisture is presentinside the piping. In addition, even if a very small amount of moistureis present in the piping, it can be efficiently removed by repeatedlyperforming steps S5 and S6, during a cleaning process performed beforeand after maintenance and repair. Thereafter, the valves V7, V11, and V4are closed, and the valves V0 and V10 of an inlet and an outlet portside of the liquid source tank 11 are opened, so that PET inside theliquid source tank 11 is sent by helium gas pressure and would flow inthe liquid source feed passage 12 of a vacuum atmosphere, therebyfilling the liquid source feed passage 12. Such a cleaning process isperformed, for example after constructing a piping in a new installationof a device, and then, a film forming process of tantalum oxide isperformed.

The aforementioned cleaning process performed before and aftermaintenance and repair is performed by controlling the opening/closingof each valve, on the basis of a program stored in the memory of thesystem controller for controlling overall operations of the processingdevice.

In accordance with such a cleaning method, since PET and/or washingfluid present inside the piping is discharged by the nitrogen gas, theliquid mentioned above can be quickly removed and amount of residualliquid present can be suppressed to a very small amount. Further, evenin case where a very small amount of liquid is present in the piping, itis discharged with the nitrogen gas, since the nitrogen gas substitutedfor the liquid described above is vacuum exhausted. As a result, PET orthe washing fluid can be removed rapidly and reliably. Still further,the air present in the piping is discharged. Therefore, even in casewhere PET of a raw material gas, which is sensitive to moisture, issupplied after cleaning, a problem such as solidification of PET doesnot occur.

Still further, the present invention is not limited to a processingdevice having a configuration that a liquid source is vaporized in avaporizer to supply into a processing vessel, but it may be applied to aprocessing device configured such that the liquid source is supplied ina liquid state and vaporized in the processing vessel.

1. A processing device, comprising: processing vessel in which a processis performed on an object to be processed by using a liquid source; aliquid source feed passage installed so as to supply the liquid sourceinto the processing vessel from a liquid source feed source; a flowcontroller, installed at the liquid source feed passage, for controllinga flow rate of the liquid source flowing through the liquid source feedpassage at a target flow rate; a washing fluid feed passage installed soas to supply a washing fluid from a washing fluid feed source to anupstream side of the flow controller in the liquid source common washingfluid feed source for feeding the washing fluid to the first and thesecond washing fluid feed passage.
 2. The processing device of claim 1,further comprising a flow adjuster, which is installed at the part ofthe washing fluid feed passage and controls a flow rate of the washingfluid supplied into the liquid source feed passage through the part ofthe washing fluid feed passage.
 3. The processing device of claim 1,further comprising a flow adjuster, which is installed at an upstreamside of the part of the washing fluid feed passage and at least controlsa flow rate of the washing fluid supplied into the liquid source feedpassage through the part of the washing fluid feed passage.
 4. Aprocessing device, comprising: a processing vessel in which a process isperformed on an object to be processed by using a liquid source; aliquid source feed passage installed so as to supply the liquid sourceinto the processing vessel from a liquid source feed source; a flowcontroller, installed at the liquid source feed passage, for controllinga flow rate of the liquid source flowing through the liquid source feedpassage at a target flow rate; a testing unit for having at least one ofa function for measuring a flow rate of a washing fluid flowing throughthe testing unit and that for controlling the flow rate of the washingfluid flowing through the testing unit at a target flow rate; a firstwashing fluid feed passage connected to the liquid source feed passage,and installed such that the washing fluid is supplied to an upstreamside of the flow controller in the liquid source feed passage withoutpassing through the testing unit; and a second washing fluid feedpassage connected to the liquid source feed passage and, at the sametime, having a part where the testing unit is placed, the second washingfluid feed passage being installed such that the washing fluid issupplied to an upstream side of the flow controller in the liquid sourcefeed passage through the testing unit.
 5. The processing device of claim4, wherein at least a portion of the first washing fluid feed passage isshared with at least a portion of the second washing fluid feed passage.6. The processing device of claim 5, further comprising a flow adjusterinstalled at a part of the first washing fluid feed passage not sharedwith the second washing fluid feed passage.
 7. The processing device ofclaim 5, further comprising a flow adjuster installed at an upstreamside of the testing unit in said at least the portion of the firstwashing fluid feed passage shared with the second washing fluid feedpassage.
 8. The processing device of claim 4, further comprising acommon washing fluid feed source for feeding the washing fluid to thefirst and the second washing fluid feed passage.
 9. A method ofmaintaining a processing device in which a liquid source is suppliedinto a processing vessel through a flow controller installed at a liquidsource feed passage, the method comprising: cleaning process forcleaning the liquid source feed passage by flowing a washing fluid tothe liquid source feed passage at a first flow rate; and testing processfor testing the flow controller by flowing the washing fluid to the flowcontroller at a second flow rate, wherein the testing process includesthe steps of, flowing the washing fluid to the flow controller through atesting unit having at least one of a function for measuring a flow rateof the washing fluid and that for controlling a flow rate of the washingfluid at a target flow rate, comparing a target flow rate of the washingfluid set in the flow controller with an actual flow rate of the washingfluid measured by the testing unit in case of flowing the washing fluidto the flow controller through the testing unit, or comparing an actualflow rate of the washing fluid measured by a flow sensor prepared in theflow controller with a target flow rate of the washing fluid set in thetesting unit in case of flowing the washing fluid to the flow controllerthrough the testing unit, and determining whether the flow controllerproperly operates or not on the basis of the comparison.
 10. The methodof maintaining a processing device of claim 9, wherein in the cleaningprocess, the washing fluid is supplied into the liquid source feedpassage without passing the testing unit, and wherein the first flowrate is greater than the second flow rate.